Detachable chainring assembly

Abstract

A detachable chainring assembly includes a first chainring, a second chainring and a locking part. The first chainring includes a first through hole. The second chainring includes a first surface, a second surface, a driven hole, and a plurality of first protrusion parts. The second surface is opposite to the first surface. The driven hole runs through the first surface and the second surface for securing a driving portion of a crank arm. The first protrusion parts protrude from the second surface and are disposed around the driven hole, and at least one of the first protrusion parts has a first locked hole. The locking part is detachably secured to the first through hole and the first locked hole such that the first chainring and the second chainring are jointly secured to each other via the locking part.

What is claimed is: 
     
       1. A detachable chainring assembly, comprising:
 a first chainring, comprising a first through hole running through the first chainring; 
 a second chainring, comprising:
 a first surface; 
 a second surface opposite to the first surface; 
 a driven hole running through the first surface and the second surface for securing a driving portion of a crank arm; and 
 a plurality of first protrusion parts protruding from the second surface and disposed around the driven hole, wherein at least one of the first protrusion parts has a first locked hole; and 
 
 a locking part, detachably secured to the first through hole and the first locked hole such that the first chainring and the second chainring are jointly secured to each other via the locking part. 
 
     
     
       2. The detachable chainring assembly according to  claim 1 , wherein the second chainring comprises an installation portion having an open slot and a side wall disposed around the driven hole, and when the driving portion of the crank arm is secured to the driven hole, the driving portion of the crank arm is disposed in the installation portion and abutted against an inner surface of the side wall, and a body of the crank arm is disposed in the open slot. 
     
     
       3. The detachable chainring assembly according to  claim 1 , wherein the first chainring comprises a plurality of second protrusion parts disposed in a surface of the first chainring away from the second chainring, the first through hole is disposed in one of the second protrusion parts, the second protrusion parts are aligned with the first protrusion parts and the first through hole is aligned with the first locked hole, and the locking part is secured to the first through hole and the first locked hole such that the first chainring and the second chainring are jointly secured to each other via the locking part. 
     
     
       4. The detachable chainring assembly according to  claim 1 , further comprising a third chainring detachably secured to the first chainring, wherein the first chainring is disposed between the second chainring and the third chainring. 
     
     
       5. The detachable chainring assembly according to  claim 4 , wherein the locking part detachably runs through the first locked hole to secure the first chainring, the second chainring and the third chainring. 
     
     
       6. The detachable chainring assembly according to  claim 4 , wherein the third chainring comprises at least one second through hole disposed in a surface of the third chainring from the second chainring, and the second through hole is aligned with the first locked hole of the first protrusion part. 
     
     
       7. The detachable chainring assembly according to  claim 1 , wherein the driven hole has a spline edge. 
     
     
       8. The detachable chainring assembly according to  claim 7 , wherein the driving portion of the crank arm comprises a jogged part for engaging the driven hole. 
     
     
       9. The detachable chainring assembly according to  claim 8 , wherein the jogged part has a spline structure for joggling the spline edge of the driven hole. 
     
     
       10. The detachable chainring assembly according to  claim 1 , wherein at least one of the first protrusion parts has a curved surface.